FIFA 11+ KIDS in the prevention of soccer injuries in children: a systematic review

Background The “FIFA 11+” is an injury prevention program conceived for soccer athletes aged over 14. The use of FIFA 11+ Kids in soccer was associated with a reduction of the overall risk of injuries in children by 48%, and of 74% for serious injuries. However, to the best of our knowledge, a systematic review of the literature on the effects of FIFA 11+ Kids is still missing. Therefore, a systematic review was conducted to ascertain the benefits of the “FIFA 11+ KIDS” program in children who practice soccer. Methods This systematic review was conducted according to the PRISMA recommendations and prospectively registered in PROSPERO. The electronic search was conducted in the following databases: Web of Science, PubMed, Medline via Ovid, EMBASE and SportDiscuss via EBSCO. Database searches were performed in January 2024. This review included studies that evaluated the effects of the “FIFA 11+ KIDS” program. Eligible studies had to describe program implementation and the mean age of the children. Results A total of 11 articles were included in this systematic review from a pool of 8513 articles screened across various databases. These articles involved over 10,000 young participants from 8 countries, primarily aged 7–14 years, with the majority being soccer athletes. Study quality varied, with four categorized as high, four as good, and three as fair quality. Objectives varied across studies, with four focusing on FIFA 11+ Kids' efficacy in injury prevention, five examining its impact on performance and physical abilities, and two assessing its effects on children's focus and attention skills. Notably, injury prevention studies reported around a 50% reduction in overall injuries and nearly 60% in severe injuries, with a dose–response relationship observed with increased weekly sessions. Significant improvements were noted in physical and functional tests such as the Y balance, jump tests, and various soccer skills, along with positive effects on children's focus and attention, as indicated by 13–18% improvements in Attention Scale for Elementary School Children (ASESC) scores. Conclusion The FIFA 11+ KIDS injury prevention program appears to be effective in reducing injuries in young football players. This can positively influence player and team overall performance and might support the long-term athlete development of these young athletes. These findings highlight the importance and necessity of injury prevention in young athletes.


Introduction
Physical activity and a healthy lifestyle from a young age can promote a lifetime of healthy, active behaviour [7,20,30].Soccer is one of the most commonly practised sports by young people around the world [8].However, the epidemiology of injuries in children who practice soccer remains unclear [9,28,29].particularly in the age group of 7 to 12 years, where injury patterns differ from those in adults.Preventive programs tailored to the type of sport and skeletal maturity of children are essential [15,27,28,37] and the traditional "FIFA 11+ ", also known as "11+ " [13,22,[32][33][34], is an injury prevention program designed for soccer athletes aged over 14, which has also been validated in other disciplines [1,14,17,29,32].The FIFA 11+ Kids program focuses on (1) spatial orientation, anticipation, and attention, particularly during dual tasking to avoid unintentional contact with other players or objects; (2) body stability and movement coordination, which is more general than specific neuromuscular or proprioceptive training; and (3) learning proper fall techniques to minimize the consequences of unavoidable falls [26].The use of FIFA 11+ Kids in soccer has been associated with a reduction in the overall risk of injuries in children by 48%, and 74% of serious injuries [27,40,42].Therefore, a systematic review was conducted to identify the benefits and applications of the "FIFA 11+ KIDS" program in children.

Eligibility criteria
This review included studies that evaluated the effects of the "FIFA 11+ KIDS" program.Eligible studies described the implementation of the program and the mean age of the included children, with the maximum age being 14 years, regardless of gender.Only studies investigating the effect of the "FIFA 11+ KIDS" program in soccer were considered.Studies that did not report the duration or frequency of the program were excluded, as well as those that did not specifically mention the "FIFA 11+ KIDS" program.Only articles published in English, German, Portuguese, Spanish, French, and Italian were considered.No additional filters were applied to the database searches, and no time constraints were imposed.Grey literature, theses and dissertations were not considered.

Search strategy
This systematic review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) recommendations [19] and prospectively registered in PROSPERO (ID: CRD42022330012).The electronic search was performed across multiple databases, including Web of Science, PubMed, Medline via Ovid, EMBASE, and SportDiscuss via EBSCO, in January 2024.Various keywords were utilized in the search strategy, with adjustments made for each platform as necessary (see Table 1).

Screening
Data extraction and study selection were independently conducted by two reviewers (**;**).The eligibility criteria were initially applied to exclude titles, followed by abstracts, and finally full articles.Additionally, the bibliography of the included studies underwent manual screening.In cases where consensus could not be reached between the two reviewers, a third reviewer (**) was consulted.

Methodological quality and data synthesis
The methodological quality of the studies was assessed using the PEDro scale, which is based on the Delphi list [39,44].This scale comprises 11 questions, of which only 10 are scored, resulting in a scale ranging from 0 to 10.Each criterion is scored based on its presence or absence in the study being assessed.The final score is determined by summing all positive responses.The PEDro scale evaluates internal validity (items 2-9), statistics and results (items 10-11), and external validity (item 1).
A study is considered of high quality if it scores greater than 50% of its maximum possible score [24,25,38,39].However, given the inherent challenges in achieving certain conditions, such as blinding therapists or subjects in intervention studies, the maximum score for an intervention study should be around 80% [16].Therefore, studies with a score greater than or equal to 8 were considered to have high methodological quality.Conversely, studies with a score of less than 3 were excluded from the present study because of their poor methodological quality.

Study selection
A total of 8513 articles were identified during the database search.After removing duplicates (N = 1464) screening titles (N = 6961) and abstracts (N = 79) that did not match the topic, a further 8504 articles were excluded.Nine articles met the inclusion criteria initially.Additionally, two articles were identified during the bibliography screening.Thus, a total of 11 articles were included in the literature search [3,5,23,26,27,30,35,36,[41][42][43] (Fig. 1).

Quality of included studies
Studies varied in quality, with scores ranging from 5 to 9 on the PEDro scale.Four studies were categorized as high-quality [23,26,35,42], four studies as good quality (5 to 7), and three studies as fair quality (4).Most studies adequately reported baseline characteristics between groups, interventions, and results.However, the lack of blinding and allocation concealment were commonly reported limitations highlighted by the PEDro score (Table 2).

Characteristics of included studies
The extracted data including outcome measures associated with FIFA 11+ are summarized in Table 3.The analysis included more than 10,000 young participants from 8 different countries.The participants ranged in age from 7 to 14 years, with only 10% (107) not being athletes.All athletes included in the analysis were soccer players.Furthermore, four studies (36.3%) had a sample size exceeding 100 participants.

Objectives
Four studies verified the efficacy of FIFA 11+ Kids in preventing injuries in young soccer athletes [3,27,30,42], while five studies focused on improving athletes' performance and physical abilities [23,26,35,41,43].One study analyzed the effects of FIFA 11+ Kids on attention, focus, and physical skills [36], and another study investigated whether FIFA 11+ Kids improved attention and focus skills [5].Injury prevention studies utilized face-toface or online monitoring methods to track injury incidence, with data often provided directly by team coaches.Among the physical and functional tests employed, the Y balance, jumping tests, and assessments of skills such as dribbling and agility were most commonly utilized.

Injury rate
Four studies (with a total of 8752 young athletes) evaluated the injury index as the main outcome [3,27,30,42].These studies observed a reduction rate of approximately 50% in injuries resulting from sports practice and almost 60% in the incidence of severe injuries (defined as time away from work > 28 days), with values of 0.13 injuries per 1,000 h of exposure in the experimental group and 0.31/1,000 h in the control group [27,42,43].Furthermore, a greater number of weekly sessions contributed to a greater reduction in the incidence of injuries, with evidence of a dose-response relationship [4,27,42,43].

Performance
Five studies (involving 277 young athletes) assessed performance and physical abilities as the main outcomes [23,26,35,41,43].The studies collectively show the FIFA 11+ Kids program positively affects various aspects of physical performance in young football players.Tests like Y balance, jump tests, dribbling, and agility consistently improved following the interventions.For example, Pomares-Noguera et al. [23] observed enhancements in dynamic postural control, agility, vertical and horizontal jump height, and accuracy in ball throwing among male youth soccer players after implementing the program.Similarly, Rössler et al. [26] noted significant improvements in motor performance, especially in Y balance and agility running tests, in children aged 7 to 12 years participating in the program.

Focus and attention
Two studies analysed the effects of FIFA 11+ KIDS on the focus and attention of children [5,36].The total score of the Attention Scale for Elementary School Children (ASESC) improved by 13% to 18%.

Discussion
The FIFA 11+ injury prevention program for kids primarily targets improvements in coordination and balance, strengthening of leg muscles, and optimization of landing techniques.As demonstrated in this study, FIFA 11+ KIDS proved to be significantly more effective than control programs in reducing injury rates, enhancing performance, and improving focus and attention.
Recent findings from a systematic review and metaanalysis revealed that FIFA 11+ Kids significantly reduces injury risks among young football players [40].This analysis, incorporating six studies from January 2016 to August 2022, demonstrated a notable decrease in overall injury risk, severe injuries, as well as specific injuries to the lower extremities, knees, and ankles.These results provide robust support for the widespread implementation of FIFA 11+ Kids as an effective injury prevention strategy in youth football.
Our study aimed to investigate additional performance and mental health variables beyond injury rates, showcasing the broader impact of the FIFA 11+ KIDS program.This intuitive program requires only 20 min to complete, progressing through 5 stages of increasing difficulty with 7 exercises each, accommodating varying levels of motor skill development [31].Initially designed for youth soccer injury prevention, FIFA 11+ KIDS has proven adaptable to diverse populations, including non-athletic children [10].Moreover, it has shown effectiveness in enhancing various outcomes, including performance, focus, and attention [6,12,36].
Enhancing children's focus and attention through interventions such as the FIFA 11+ KIDS program can lead to improved learning outcomes and academic performance, as these cognitive functions are integral to academic success [12].Educational administrators and teaching staff in elementary schools must consider implementing physical activity interventions, such as the FIFA 11+ KIDS program, to enhance the fitness levels and overall well-being of school children.
The implementation of the programme in schools can be a challenge, as the intensity and duration of the training intervention might not be feasible in many settings [18].Adjustments to fit the needs of schools are recommended, and modifying the frequency and duration of the FIFA 11+ KIDS or changing the schedule of exercise interventions could be considered [10].
The FIFA 11+ KIDS program has demonstrated remarkable effectiveness in preventing football injuries, surpassing conventional warm-up routines by reducing overall injuries by at least 50% and severe injuries by almost 60%.Similar assessments of the FIFA 11 and FIFA 11+ programs in adult football players have shown a significant reduction in injury risk, with football injuries decreasing by 39% [2,31,36].These findings underscore the substantial impact of FIFA's injury prevention initiatives in mitigating injury rates in both adult and child football players.
Decreasing injury incidence not only enhances performance throughout a sporting season but also fosters improved athletic development among young athletes [11].Moreover, injury reduction initiatives such as the 11+ KIDS program can yield long-term benefits.One factor that may hinder the program's effectiveness is the low adherence among young athletes and coaches.Higher completion rates of the FIFA 11+ KIDS program are associated with greater protective effects [2].Coaches may exhibit resistance to change, opting to stick to familiar routines or traditional warm-up exercises.Similarly, athlete non-compliance can lead to suboptimal execution of the program or high dropout rates [21].
The inclusion of studies with varied outcome measures limited the direct comparison of intensities and 1. Eligibility criteria were specified 2. Subjects were randomly allocated to groups 3. Allocation was concealed 4. The groups were similar at baseline regarding the most important prognostic indicators 5.There was blinding of all subjects 6.There was blinding of all therapists who administered the therapy 7.There was blinding of all assessors who measured at least one key outcome 8. Measures of at least one key outcome were obtained from more than 85% of the subjects initially allocated to groups 9.All subjects for whom outcome measures were available received the treatment or control condition as allocated or, where this was not the case, data for at least one key outcome was analyzed by "intention to treat" 10.The results of between-group statistical comparisons are reported for at least one key outcome    efficacy of protocols across studies.Statistical analysis, such as examining the relationship between outcomes, was beyond the scope of this systematic review.However, such analyses could offer valuable insights into optimizing the prescription of the FIFA 11+ KIDS protocol.Future studies could explore the transferability of the FIFA 11+ KIDS program to other team sports.

Limitations
While the FIFA 11+ Kids program holds promise to improve injury prevention in young athletes, its effectiveness remains less clear compared to the well-established adult FIFA 11+ program.The current body of research is limited, particularly regarding adherence rates, which can vary depending on factors like the specific program format, study population characteristics, and methodological approaches.Some studies report high adherence, while others show lower rates because of lack of motivation or logistical challenges.Analysing adherence data from each study would provide a precise range, but unfortunately, these data are missing from the reviewed studies.This lack of data hinders our ability to draw definitive conclusions about the program's long-term impact on injury reduction and its suitability for different age groups, genders, and skill levels.Future investigations should explore the implementation of FIFA 11+ Kids in broader demographics, accounting for factors such as athlete characteristics and training environments.Additionally, employing robust methodologies that capture adherence data will be crucial for establishing the program's effectiveness and identifying optimal use guidelines.

Conclusion
The FIFA 11+ KIDS injury prevention programme demonstrates effectiveness in reducing injuries in young football players, potentially enhancing both individual player and team performance.These outcomes underscore the significance of injury prevention initiatives in young athletes, particularly those engaged in high-performance sports, and emphasize the importance of implementing such programmes for long-term athlete development.

Figure 1
Figure 1 Flow chart of the search process

Table 1
Search strategya Search strategy used in Medline (the strategy was modified according to the specifics of each database)

Table 2
Methodological quality assessment (PEDro score) 11.The study provides both point measures and measures of variability for at least one key outcome

Table 3
Generalities and patient characteristics of the included studies